Method for producing a punch

ABSTRACT

A method for producing a punch for single-step forming a spinneret nozzle having a plurality of slot-like segments includes broaching an appropriately sized hole drilled into one end of soft punch stock to form the inside dimensions of the segments, then machining the punch stock to the outside dimensions of the segments and slotting and removing a portion of the punch at its tip end to form a plurality of male arcuate die segments. The tool is then heat treated.

United States Patent 1 1 Hawkins Oct. 30,1973

METHOD FOR PRODUCING A PUNCH lnventorz. Curtis Owen Hawkins, Cove City,

Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

Filed: June 14, 1972 Appl. No.: 262,493

U.S. Cl 76/107 S, 76/107 Int. (:1 821k 5/20 Field of Search 76/107 R, 107 A,

References Cited UNlTED STATES. PATENTS 1/1937 Tomalis 76/107 R 8/1958 Kopczynski 76/107 R 3,190,107 6/1965 Slifka et a] ..l 76/107 5 Primary Examiner-Harrison L. Hinson Attorney--Howard P. West, Jr.

[57] ABSTRACT A method for producing a punch for single-step forming a spinneret nozzle having a plurality of slot-like segments includes breaching an appropriately sized hole drilled into one end of soft punch stock to form the inside dimensions of the segments, then machining the punch stock to the outside dimensions of the segments and slotting and removing a portion of the punch at its tip end to form a plurality of male arcuate die segments. The tool is then heat treated.

2 Claims, 1t) Drawing Figures PAIENIEDnm 30 I973 sum 10F 2 FIG-Z FIG-l F l GiZA FIG-4 FIG-I3 METHOD FOR PRODUCING A PUNCH BACKGROUND OF THE INVENTION This invention relates to a new method for forming a punch for the fabrication of spinneret capillaries.

spinneret capillaries used to form hollow filaments by polymer coalescence below the face of the spinneret require a complex nozzle. These nozzles are made up of a plurality of short, shaped slots or orifices separated by webs of metal to provide points where air can enter the filaments and to provide support for the internal portion of the orifice. Preferably, the slots are shaped so as to provide more polymer at the ends of the slots.

In order to reduce tedious and time consuming aspects of orifice fabrication, it is desirable to be able to form the multi-segment nozzle with a single punch in one operation. However, punches having complexshaped inner surfaces are practically impossible to machine.

SUMMARY OF THE INVENTION A method for producing a die punch tool from soft punch stock for forming a complex spinneret nozzle having a plurality of slots each of said slots having inner and outer configurations, said method comprising: machining a hole axially into one end of said soft punch stock; broaching said hole to conform to the inner configuration of said slots in said hole; machining the outer portion of said stock to conform to the outer configuration of said slots; removing punch stock material to form male die segments; and hardening the stock.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 1a are partial elevation and end views, respectively, of a broach which may be used in producing a punch tool.

FIGS. 2 and 2a are partial top and elevation views, respectively, of a section of punch stock drilled to accept the broach of FIG. 1.

FIGS. 3 and 3a are top and elevation views similar to FIGS. 2 and 2a after broaching.

FIGS. 4 and 4a represent partial end and elevation views of the punch stock of FIGS. 2 and 3 after the machining is complete.

FIGS. 5 and 6 illustrate orifice configurations that can be made with a punch made according to the in vention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring now to FIGS. l-3a, a forming tool or broach 10 having a round stem 12 extending from tapered shoulder 14 has grooves 16 milled into stem 12. This broach 10 is used to form the inner configuration of the punch tool in punch stock 20 which is axially drilled with holes 22, 24. The hole 22 is the same diameter as the stem 12 of broach 10 and serves as a starter or guide hole. The diameter of hole 24 is the same as the smallest distance between two opposed grooves 16 in broach 10, e.g., dimension s in FIG. 1a. In producing a punch in accordance with thepresent invention, the forming tool is forced down into the drilled punch stock to a depth such as that shown by arrow B in FIG. 3a to produce a shaped internal surface having four protrusions 26. The thusly shaped punch stock is then machined to provide a punch 30 having a tapered shoulder 32 and round stem 34, the outer surface of stem 34 will determine the outer configuration of spinning nozzle slots punched in a spinneret. Slits 36 are then cut into the terminal portion of the stem 34. The center of the slits corresponds to the longitudinal axis of the grooves. The tip end of the stem 34 is then removed at least as far back as the bottom of the starter hole 22 to form the punch which is then heat treated and polished. The finished punch 30 terminates in four arcuate male die segments 38 having tapered inwardly extending enlargements 40.

The forming tool or broach 10 will ordinarily have the round stem 12 as shown but may be machined to other shapes. The grooves 16 machined into the broach will determine, at least in part, the shape of the enlargements 40 of the arcuate die segments 38 of the punch. The grooves 16 may be of any suitable cross-sectional configuration but preferably will be rounded rather than angular. When the distance from the center of the broach 10 to the bottom of groove 16 is the same as or slightly greater than the radius of the hole 24, the shape of the forming tool will determine the shape of the inner configuration of the stock hole 24. This shape in turn determines the inner configuration of spinning nozzle slots punched in a spinneret. When the above referred-to distance is less than the radius of the smaller hole, the innermost part of the enlargements can be an are formed from the wall of the drilled hole 24.

FIG. 5 illustrates one of a plurality of spinning nozzles 50 usually provided in a spinneret plate as formed by a punch tool similar to that illustrated in FIGS. 4, 4a. There are four arcuate slots 38a which are separated by webs 36a. The inner and outer configurations of the slots as referred to above are the surfaces designated 35 and 37, respectively.

Shown in FIG. 6 is another orifice configuration that can be provided with a punch of this invention. Nominal values for dimensions indicated in this figure are: a, 0.033 inch; b, 0.004 inch; c, 0.003 inch; d, 0.0065 inch; e, 0.002 inch; R, 0.008 inch; r, 0.003 inch. If desired, the line represented by radius R may be replaced by a straight line which may form an angle with the end of the segment as indicated at h and wherein a nominal value for h may be 45.

Although this invention has been illustrated with respect to a four-segment punch, it will be obvious that punches with two or more segments could be described. It is, of course, not necessary that the configurations correspond to pure circles or that the enlargements be of the same size and shape.

What is claimed is: I

1. A method for producing a die punch tool from soft punch stock for forming a complex spinneret nozzle having a plurality of slots each of said slots having inner and outer configurations, said method comprising: machining a hole axially into one end of said soft punch stock; broaching said hole to conform to the inner configuration of said slots; machining the outer portion of said stock to conform to the outer configuration of said slots; removing punch stock material to form male die segments; and hardening the stock.

2. The method of claim 1, said nozzle having four slots, the removing step comprising slitting and removing a portion of said one end to form four extending male die segments. 

1. A method for producing a die punch tool from soft punch stock for forming a complex spinneret nozzle having a plurality of slots each of said slots having inner and outer configurations, said method comprising: machining a hole axially into one end of said soft punch stock; broaching said hole to conform to the inner configuration of said slots; machining the outer portion of said stock to conform to the outer configuration of said slots; removing punch stock material to form male die segments; and hardening the stock.
 2. The method of claim 1, said nozzle having four slots, the removing step comprising slitting and removing a portion of said one end to form four extending male die segments. 